Expansible anchor bolt and method of anchoring same



March 1963 F. F. LINDSTAEDT ETAL EXPANSIBLE ANCHOR BOLT AND METHOD OF ANCHORING SAME Filed March 24, 1958 2 Sheets-Sheet 1 n .I I

. 5 A v v n m n :v

INVENTORS Frank E Lindsfaedt v 2 I. 0. v. n v 4 I I. ro In o A b 0 0 0/ a 4.:

I. n A

. p b a n n 0 .u. l P o .n a

Jerry F. Hamlin Hughes Call ATTY.

March 1963 F. F. LINDSTAEDT ETAL 3,032,578

EXFANSIBLE ANCHOR BOLT AND METHOD OF ANCHORING SAME Filed March 24, 1958 2 Sheets-Sheet 2 INVENTORS Frank F. Lindsfaedr Jerry F. Hamlin Hughes Call AITY.

United States Patent M 3,982,578 EXPANSIELE ANCHSR BQLT AND METHQD r 9F ANCHGRlNG EAR/1E rrank F. Llndstaedt, San Anselmo, (Ialif. (4-020 Lush A ve., Sacramento 2S, filaliii}, Jerry F. Hamlin, 42 Gal;- rr lge Road, San Rafael, Calif and Hughes Call, 515 lviontford Ava, Mill Valley, (Ialif.

Filed Mar. 24, 1958, Ser. No. 723,387 17 Claims. (Cl. 50-531.)

The present invention relates to improvements in a method of and means for anchoring bolts in concrete, and its principal object is to provide an anchoring means which is simple and easy to apply, has tremendous holdmg power, relies on chemical action, and may be applied to concrete walls and ceilings as well as to concrete foundations.

More particularly, it is proposed to use a stack of tablets of a special expandable binding composition alternating with layers of sponge, the stack being adapted for encircling the bolt and fitting within the bolt hole provided in the concrete. The tablets are made to pulverize when the stack is driven into the hole and the la ers of sponge are made to deliver water to the powdered tablet material for causing the latter to expand against the shaft and the wall before it sets.

It is still further proposed to provide a special expandable composition greatly increasing the expansive force of the chemical.

And finally, it is proposed to provide the stacks in convenient units easy to manufacture and market and to apply the same at the place of use without the need of any special tools.

Further objects and advantages or our invention will be apparent as the specification proceeds, and the new and useful features of the same will be fully defined in the claims attached hereto.

The preferred forms of our invention are illustrated in the accompanying drawing, forming part of this application, in which:

FlGURE 1 shows a vertical section through a stack of alternate layers of expandable binding mixture and sponge as applied to a bolt and a bolt hole, representing the first step in the application of our invention;

FIGURE 2, a similar section showing the stack in hammered-down position, representing the second step;

FIGURE 3, a similar section showing a new stack placed on top of the previously applied stack, as the third step in the method;

FIGURE 4, a similar section showing the anchor in final form;

FIGURE 5, shows a vertical section of the invention, where the latter is applied to a female coupler;

FIGURE 6, a slight modification of FIGURE 5, and

FIGURE 7, a perspective detail view of a single stack unit as used in he various forms.

While we have shown only the preferred forms of our invention, it should be understood that various changes or modifications may be made within the scope of the claims hereto attached, without departing from the spirit of the invention.

Referring to the drawings in detail, and particularly to the form shown in FIGURE 1, the bolt l is formed with a conventional head 2 at one end and a thread 3 at the opposite end is made for insertion into the hole 4 drilled in a body of concrete 5.

The bolt shank 6 is made of a desired thickness to meet requirements, say, one-half an inch, and the hole in the concrete is made of a length and diameter to allow the major porton of the bolt to be inserted thereinto, head first, as shown, with a portion of the bolt projecting from the face of the concrete to serve as a securing means for an object placed on the concrete surface.

3,332,578 Patented Mar. 26, 1963 The anchoring means comprises a stack or column of alternate layers of plastic composition 7 and sponge 8. The layers of plastic composition, also referred to as tablets, are cylindrical in shape and formed with central holes 9 fitting on the shank of the bolt. Their outer diameter is made approximately the same as the diameter of the bolt head and somewhat less than the inner diameter of the hole in the concrete so as to insure an easy sliding fit, even in the case of slight irregularities in the diameter and shape of the hole, and to leave an annular chamber or space 10 between the shank and the hole.

The tablets preferably have a length comp-arable, more or less, with their diameter. The tablets are preferably made according to the following formula:

Ingredients: Grams Ammonium aluminum sulphate 1.4 Ground compressed saw-dust (an example is ground PrestoLog) 4.0 Specially prepared anhydrous calcium sulphate with properties similar to hydrostone 200.60

Thoroughly mix the above ingredients, then add: 40.0 mils of El /2% zinc resinate in isopropyl alcohol.

Granulate the mixture through a one-eighth inch screen and allow to dry. The dry granules are then compressed into tubular tablets.

The sponge layers or collars 8 are cut from thin sheets of cellular synthetic sponge, such as cellulose sponge, or polyurethane foam or any similar material. Any sponge material that readily absorbs water may be used, but the preferred material is synthetic foam sponge of the open cell type.

With respect to size, the foam-sponge collars 8 have the same OD. and ID. as the tubular tablets, but they are comparatively rather thin, varying from one-eighth of an inch to one-quarter inch. Functionally, the thickness of the foam collars is determined precisely by the amount of water required to cause the tablets to expand and set. Thus, the foam collar thickness is engineered to carry the correct amount of water required for the particular tablet with which it is used. The moisture required varies typically from 15% to 30% moisture by weight with regard to weight of the tablet with which it is used.

A preferred method of employing the alternating sponge-tablet-sponge relationship is to pre-assemble five elements into a single unit (see FIGURE 7) at the point and time of manufacture of the tubular tablets in the following manner.

Two tubular tablets are sandwiched in between three foam-sponge collars with the centerholes registered. The five elements are held together with a water-pervious adhesive of silicate of soda (as exemplified by N brand, made by Philadelphia Quartz Company) in a syrupy form, or similar material, by applying such adhesive to the common or adjacent faces of the fiv elements.

The result is the formation of a long sleeve with a thin sponge at either end, and a sponge collar in the middle which is twice the thickness of the sponge collar at either end.

To use this pre-assembled sleeve, the operator slips one or more of them on the bolt (two being shown in FIG- URE l), and thus achieves the same result as the individual element stacking of alternate sponge-tablet-sponge, but with less effort and time involved. The pro-assembly method is more eflicient in that every tablet is assured of beiru next to a spon e, and the end-sponges protect the tablets in transportation and general handling.

Enough sponge collars and tablets are stacked on the shaft of the bolt to equal the depth of the hole prepared for the bolt (see FIGURE 1). Following this, the entire assembly is immersed in water which is deep enough to cover all the tablets and all the sponges. the assembly is held under water varies with the chemical composition of the tablets and the type and thickness of the sponge collars used, but will range from approximately five seconds to sixty seconds.

The assembly is withdrawn from the water and placed in the hole, the bolt being pushed in until the head of the bolt rests against the bottom of the hole. Next, the sponges and tablets are squeezed and pressed down into the hole by the action of placing a short length of pipe 11 down over the shaft of the bolt and striking the pipe with a hammer four or live times. The pipe permits the sponges and tablets, and not the bolt shaft, to receive the hammer blows.

Hammcring the sponges and tablets down into the hole has two results. First, it squeezes water out of the sponges, and secondly, it breaks up the tablets into a more or less powder condition. The powder absorbs the water, and begins to expand immediately.

When the assembly of sponges and tablets, riding the bolt, is lowered into the hole, there is a gap between the sponge-tablet combination, and the wall of the hole, because by design the 0.1). of the sponges and tablets is less than the diameter of the hole in which they are used. This gap is filled up however, by the action of driving the sponges and tablets inward by the hammer blows.

The result is that the level of the sponge-tablet mass is now less than sufficient to fill up the hole, as shown in FIGURE 2. The operator then adds (see FIGURE 3), another sponge-tablet-sponge combination, first dipping it in water the required time, placing it on the bolt, and drives it into place in the manner described above.

Lastly, the lead Washer 12 is slipped on the bolt shaft, and with the pipe hammer arrangement, is driven down into the mouth of the hole. Being fractionally oversize, it forms a force fit. By being driven down as far as it will go under hammer blows, it performs two functions.

First, it holds the wetted chemical sponge-tablet mass in a state of compression until the mass has chemically set and becomes stable. Secondly, it forms a smooth fitting top, more or less flush with the surface of the concrete in which the hole was drilled.

As the water reacts with the chemical composition of the tablets, the latter expand rapidly and then set. This sequence is a feature of our invention, and if the setting occurred prior to the expansion, the chemical would not be able to hold the bolt. The problem solved by this invention is to have the chemical in a solid state to permit installation in walls and ceilings, to expand under controlled conditions, and to set as rapidly as possible after all the expansion has taken place.

Our invention is superior to existing methods of fastening bolts in concrete for the following reasons:

(1) It has greater holding ability than conventional chemicals now in use to put into bolt holes drilled in a floor. I

(2) It is infinitely stronger, and much lower in cost than mechanical devices now in use.

(3) It can be employed in walls and ceilings, in fact, anywhere, whereas existing chemicals, though strong enough where used, are limitedto pouring in a floor, and cannot be used in walls and ceilings. 1 a

(4) When used to fasten a bolt in the floor, as a substitute for existing chemicals, it eliminates heating and/ or mixing'or stirring. I

The foregoing description of how our invention functions specifically outlines the ability to anchor bolts in concrete. While this is the principal use for which it is intended, it also has use in anchoring a rod-coupler in concrete.

The rod-coupler is the female counterpart of a machine or carriage bolt, and when it has been anchored in con- The time that pontion is in jeopardy of filling with surplus overflow crete, a bolt may be screwed into it to hold down the work load firmly to the concrete ceiling, wall or floor.

Whereas, a bolt necessarily projects above the surface of the concrete in order to receive the material to be fastened, the rod-coupler is fitted in the hole flush with the surface of the concrete. Machinery or the like, to be fastened is, then registered over the rod-coupler and secured by screwing a bolt down into it. It, later it is necessary to move such machinery, the bolt (or bolts) are backed out, and the rod-coupler, permanently anchored in the concrete, is left undisturbed, ready for future use, if any, but meanwhile not impairing the usefulness of the concrete surface for some other use.

In contrast, if machinery were removed from an anchored bolt, the protruding threaded end of the bolt, unless cut olf, remains as a potential interference to some other use of the said surface. Thus, the bolt, being more economical, is used for more or less permanent installations, whereas the rod-coupler is employed where there is probability of frequent moving of machinery warrants the additional cost. i i a The rod-coupler, shown at 15, in FIGURE 5, has a smooth exterior wall, and is threaded internally throughout its length. It is typically two or three times longer than its OD. The ID. of the rod-coupler is determined by the bolt it is to receive; and the bolt size in turn is determined by the work load for which it is intended.

The rod-coupler has a smooth exterior wall, and lacks a protruding purchase-point or grip-features, such as the head of a bolt. Therefore, in order to anchor it most perfectly in the hole, a short carriage bolt 16 is screwed into one end of the rod coupler up to but not beyond onehalf of its length.

When anchoring in a hole, a totem-pole stacked unit of sponge-tablet-sponge is slipped over the rod-coupler short bolt combination and generally is anchored by the method and steps described for bolts above, except that an auxiliary device is used.

The rod-coupler being short, and fitting in the hole flush with the surface of the concrete, provides no means for holding onto it after the tablets have been stacked thereon. Moreover, the cavity of the female threaded from the wetted tablet mass. 7

To preclude this, and to provide a shaft by which to grasp the rod-coupler, a special device is required. This device is in the form of a solid metal round rod :17, which is six to eight inches in length, and having an OD. equal to that of the rod-coupler. A half-inch of one end is turned down, and threaded, enabling it to be screwed into the exposed end of the rod-coupler, as shown at 18.

This device, when screwed into the rod-coupler, provides:

(I) A convenient handle by which to manipulate the rod-coupler;

(2) A shaft on which to stack the sponge-tablet units;

(3) A closure to prevent surplus wetted expandable compound from getting into the otherwise open female aperture.

When the several steps of anchoring are completed, and the lead washer has been driven into place, the special device is unscrewed, leaving the rod-coupler clean and ready for use when the tablets have expanded and set.

A further development of the foregoing use of a rodcoupler, and stemming directly from the nature of the invention of the expandable tablets, is the new and original special device which may be described functionally as a female anchor for bolts.

Attention is invited to FIGURE 6, and it will be noted that this device is simply a one-piece unit to replace the combination of the rod-coupler and its short hold-down bolt, see FIGURE 5.

The new anchor device would be designed to receive a bolt 19, selected for the specific load it is to hold, have a wall of sufiicient dimension to serve the purpose, be

long enough to accommodate the required number of tablets, and have a head 20 at the end opposite from that of the female cavity.

It would therefore, be a conventional round rod-coupler, with the addition of a round head at one end, rather than continuous threads throughout its length. This device, together with the special handle device is applicable to the subject-matter of this invention only, for without the invention of the. Wettable expandable tablets, there would be no use for such a device.

The combination of the expandable. tablets, the female anchor for bolts, and the special handle device form a new and original of creating a flush-fit female threaded anchor for securing bolts in concrete walls, floors and ceilings.

With regard to the preferred formula, each ingredient performs a specific function, and the weight relationship has been critically determined and controlled to assure certain results, as follows:

Anhydrous calcium sulphate, when mixed with water, expands, and then sets very hard.

Compressed ground saw-dust, expands very rapidly, aiding the anhydrous calcium sulphate to expand more rapidly than it otherwise would.

Ammonium aluminum sulphate, accelerates the setting time, but the proportion of this to the other ingredients must be controlled very critically to allow the saw dust and the hydrostone to expand fully before setting, and then set very quickly.

Zinc resinate, acts as a binder in forming the granules, and because of extremely high coefiicient of friction, it prevents (following expansion and setting) slippage of one particle on another particle, and slippage as between one particle of the composition and the wall of the hole, or the shank of the bolt.

We claim:

1. In means for anchoring a bolt in concrete, a column of layers of binding composition and sponge material mounted in alternate succession and bored centrally to fit upon the shank of the bolt.

2. In means for anchoring a bolt in concrete, a column of layers of binding composition and sponge material mounted in alternate succession and bored centrally to fit upon the shank of the bolt, the layers being cylindrical and having an outer circumference substantially commensurate with that of the bolt head.

3. In means for anchoring a bolt in concrete, a column of layers of binding composition and sponge material mounted in alternate succession and bored centrally to fit upon the shank of the bolt, the layers being cylindrical and having an outer circumference substantially commensurate with that of the bolt head, the layers of sponge material being adapted to absorb water therein.

4. In means for anchoring a bolt in concrete, a column of layers of binding composition and sponge material mounted in alternate succession and bored centrally to fit upon the shank of the bolt, the layers being cylindrical and having an outer circumference substantially commensurate with that of the bolt head, the layers of sponge material being adapted to absorb water therein, and the binding material being adapted to pulverize under the blows of a hammer and to expand against the shank and a surrounding wall in the presence of the water released by the sponge material.

5. In means for anchoring a bolt in concrete, a column of la ers of binding composition and sponge material mounted in alternate succession and bored centrally to fit upon the shank of the bolt, the layers being cylindrical and having an outer circumference substantially commensurate with that of the bolt head, the layers of sponge material being adapted to absorb water therein, and the binding material being adapted to pulverize under the blows of a hammer and to expand against the shank and a surrounding wall in the presence of water released by the sponge material, and the binding composition having an expansion agent in the nature of ground compressed saw-dust therein.

6. In means for anchoring a bolt in concrete, a bolt assenpbly comprising a bolt having a shank and a head at one end thereof, and alternate layers of binding composition and sponge material arranged on the shank in alternating succession and pushed up against the head.

7. In means for anchoring a bolt in concrete, a bolt assembly comprising a bolt having a shank and a head at one end thereof, and alternate layers of binding composition and sponge material arranged on the shank in alternating succession and pushed up against the head, the sponge material being adapted to quickly absorb water when dipped into a body of water in its free state.

8. In means for anchoring a bolt in concrete, a column of alternate layers ofpulverizable water reacting expansible material and a water absorptive sponge material, said column being formed with a central axial bore adapted for fitting upon the shank of a bolt, and waterpervious adhesive between adjacent layers for securing the latter in a unit of sleeve-like form.

9. An anchoring device, comprising an elongated bolt member having an enlarged head at one end providing a shoulder facing the shank of said bolt, and a column of alternate layers of a pulverizable water reacting expansible material and a water absorptive sponge material, said column being formed with a central axial bore fitting on said bolt member against said shoulder.

10. An anchoring device, comprising an elongated bolt member having an enlarged head providing a shoulder at one end and a bore formed with internal screw threads at the other end adapted for receiving the threaded end of a tie-down bolt, and a column of alternate layers of pulverizable water reacting expansible material and a Water absorptive sponge material, said column being formed with a central axial bore fitting on said bolt member against said shoulder.

11. An anchoring device, comprising an elongated sleeve having internal screw threads formed therein, a bolt threadedly engaged in said sleeve and formed with an enlarged head providing a shoulder of larger diameter than the outside diameter of said sleeve, and a column of alternate layers of pulverizable water reacting expansible material and a Water absorptive sponge material, said column being formed With a central axial bore fitting over said bolt and sleeve and against said shoulder.

12. In means for anchoring a bolt in concrete, a column of alternate layers of pulverizable water reacting expansible material and a water absorptive sponge material, said column being formed with at least one layer of said pulverizable material with a central axial bore adapted for fitting upon the shank of a bolt, and water= pervious adhesive between adjacent layers for securing the latter in a unit of sleeve-like form.

13, The method of anchoring a bolt having an enlarged head in a hole in a rigid body such as concrete, comprising the steps of placing rings of Water absorptive sponge and a solid pulverizable water reacting expansion agent in alternating relation on the shank of said bolt, dipping said bolt and rings in water, placing said bolt in said hole with the head of the bolt inwardly thereof, and hammering said rings into said hole so as to pulverize said expansion agent rings and to compress said sponge rings and release water into the pulverized expansion agent.

14. The method of claim 13 in which a deformable washer is placed on the shank of said bolt after said rings, and said washer is hammered into said hole so as to pulverize said expansion agent rings and to compress said sponge rings and release water into the pulverized expansion agent, said washer serving to hold said expansion material in said hole during expansion.

l5. The method of anchoring a bolt having an enlarged head in a hole in a rigid body such as concrete, comprising the steps of forming rings of water absorptive sponge material and of a solid pulverizible expansion agent consisting principally of a mixture of powdered hydrostone and ground compressed sawdust, placing said rings of sponge material and expansion agent in alternating relation on the shank of said bolt, dipping said bolt and rings in Water, placing said bolt in said hole with the head of the bolt inwardly thereof, mounting a deformable washer having a diameter greater than that of said hole on said bolt, placing a length oftube against said washer, and striking said tube to hammer said Washer and said rings into said hole so as to pulverize said rings of expansion agent and to compress said rings of sponge material and release water into the pulverized expansion agent.

16. The method of anchoring a structural member in a hole formed in a body of rigid material such as concrete, which comprises the steps of inserting an end of the structural member into the hole, pounding a self-expanding and self-setting solid material in rigid form into the hole so as to pulverize and compact said material and force is into intimate anchoring contact with the walls of the hole and with said member, said material having the property of'reacting with Water to effect expansion, and introducing a controlled amount of water into said self-setting and solid material in said hole during said pounding.

17. The method of anchoring a structural member according to claim 16 and wherein an oversized washer of deformable material is hammered into said hole around said member to form a closure for said hole.

References Cited in the file of this patent UNITED STATES PATENTS 809,177 Drolshagen Jan. 2, 1906 847,471 Gross Mar. 19, 1907 877,118 Peirce -2 Jan. 18, 1908 1,120,410 Rohmer Dec. 8, 1914 1,352,201 Kennedy Sept. 7, 1920 1,702,965 Haggerty Feb. 19, 1929 1,736,294 Venz-ie Nov. 19, 1929 1,909,026 Tomkinson May 16, 1933 1,958,674 Nusbaum May 15, 1934 2,154,355 Rawlings Apr. 11, 1939 2,580,174 Henderson Dec. 25, 1951 

16. THE METHOD OF ANCHORING A STRUCTURAL MEMBER IN A HOLE FORMED IN A BODY OF RIGID MATERIAL SUCH AS CONCRETE, WHICH COMPRISES THE STEPS OF INSERTING AN END OF THE STRUCTURAL MEMBER INTO THE HOLE, POUNDING A SELF-EXPANDING AND SELF-SETTING SOLID MATERIAL IN RIGID FORM INTO THE HOLE SO AS TO PULVERIZE AND COMPACT SAID MATERIAL AND FORCE IS INTO INTIMATE ANCHORING CONTACT WITH THE WALLS OF THE HOLE AND WITH SAID MEMBER, SAID MATERIAL HAVING THE PROPERTY OF REACTING WITH WATER TO EFFECT EXPANSION, AND INTRODUCING A CONTROLLED AMOUNT OF WATER INTO SAID SELF-SETTING AND SOLID MATERIAL IN SAID HOLE DURING SAID POUNDING. 